function submit(partId)
%SUBMIT Submit your code and output to the ml-class servers
%   SUBMIT() will connect to the ml-class server and submit your solution

  fprintf('==\n== [ml-class] Submitting Solutions | Programming Exercise %s\n==\n', ...
          homework_id());
  if ~exist('partId', 'var') || isempty(partId)
    partId = promptPart();
  end
  
  % Check valid partId
  partNames = validParts();
  if ~isValidPartId(partId)
    fprintf('!! Invalid homework part selected.\n');
    fprintf('!! Expected an integer from 1 to %d.\n', numel(partNames) + 1);
    fprintf('!! Submission Cancelled\n');
    return
  end
  
  if ~exist('ml_login_data.mat','file')
    [login password] = loginPrompt();
    save('ml_login_data.mat','login','password');
  else  
    load('ml_login_data.mat');
    [login password] = quickLogin(login, password);
    save('ml_login_data.mat','login','password');
  end
  
  if isempty(login)
    fprintf('!! Submission Cancelled\n');
    return
  end

  fprintf('\n== Connecting to ml-class ... '); 
  if exist('OCTAVE_VERSION') 
    fflush(stdout);
  end
  
  % Setup submit list
  if partId == numel(partNames) + 1
    submitParts = 1:numel(partNames);
  else
    submitParts = [partId];
  end

  for s = 1:numel(submitParts)
    thisPartId = submitParts(s);
    [login, ch, signature, auxstring] = getChallenge(login, thisPartId);
    if isempty(login) || isempty(ch) || isempty(signature)
      % Some error occured, error string in first return element.
      fprintf('\n!! Error: %s\n\n', login);
      return
    end

    % Attempt Submission with Challenge
    ch_resp = challengeResponse(login, password, ch);

    [result, str] = submitSolution(login, ch_resp, thisPartId, ...
           output(thisPartId, auxstring), source(thisPartId), signature);

    partName = partNames{thisPartId};

    fprintf('\n== [ml-class] Submitted Assignment %s - Part %d - %s\n', ...
      homework_id(), thisPartId, partName);
    fprintf('== %s\n', strtrim(str));

    if exist('OCTAVE_VERSION')
      fflush(stdout);
    end
  end
  
end

% ================== CONFIGURABLES FOR EACH HOMEWORK ==================

function id = homework_id() 
  id = '1';
end

function [partNames] = validParts()
  partNames = { 'Warm up exercise ', ...
                'Computing Cost (for one variable)', ...
                'Gradient Descent (for one variable)', ...
                'Feature Normalization', ...
                'Computing Cost (for multiple variables)', ...
                'Gradient Descent (for multiple variables)', ...
                'Normal Equations'};
end

function srcs = sources()
  % Separated by part
  srcs = { { 'warmUpExercise.m' }, ...
           { 'computeCost.m' }, ...
           { 'gradientDescent.m' }, ...
           { 'featureNormalize.m' }, ...
           { 'computeCostMulti.m' }, ...
           { 'gradientDescentMulti.m' }, ...
           { 'normalEqn.m' }, ...
         };
end

function out = output(partId, auxstring)
  % Random Test Cases
  X1 = [ones(20,1) (exp(1) + exp(2) * (0.1:0.1:2))'];
  Y1 = X1(:,2) + sin(X1(:,1)) + cos(X1(:,2));
  X2 = [X1 X1(:,2).^0.5 X1(:,2).^0.25];
  Y2 = Y1.^0.5 + Y1;
  if partId == 1
    out = sprintf('%0.5f ', warmUpExercise());
  elseif partId == 2
    out = sprintf('%0.5f ', computeCost(X1, Y1, [0.5 -0.5]'));
  elseif partId == 3
    out = sprintf('%0.5f ', gradientDescent(X1, Y1, [0.5 -0.5]', 0.01, 10));
  elseif partId == 4
    out = sprintf('%0.5f ', featureNormalize(X2(:,2:4)));
  elseif partId == 5
    out = sprintf('%0.5f ', computeCostMulti(X2, Y2, [0.1 0.2 0.3 0.4]'));
  elseif partId == 6
    out = sprintf('%0.5f ', gradientDescentMulti(X2, Y2, [-0.1 -0.2 -0.3 -0.4]', 0.01, 10));
  elseif partId == 7
    out = sprintf('%0.5f ', normalEqn(X2, Y2));
  end 
end

% ====================== SERVER CONFIGURATION ===========================

% ***************** REMOVE -staging WHEN YOU DEPLOY *********************
function url = site_url()
  url = 'https://class.coursera.org/ml-004';
end

function url = challenge_url()
  url = [site_url() '/assignment/challenge'];
end

function url = submit_url()
  url = [site_url() '/assignment/submit'];
end

% ========================= CHALLENGE HELPERS =========================

function src = source(partId)
  src = '';
  src_files = sources();
  if partId <= numel(src_files)
      flist = src_files{partId};
      for i = 1:numel(flist)
          fid = fopen(flist{i});
          if (fid == -1) 
            error('Error opening %s (is it missing?)', flist{i});
          end
          line = fgets(fid);
          while ischar(line)
            src = [src line];            
            line = fgets(fid);
          end
          fclose(fid);
          src = [src '||||||||'];
      end
  end
end

function ret = isValidPartId(partId)
  partNames = validParts();
  ret = (~isempty(partId)) && (partId >= 1) && (partId <= numel(partNames) + 1);
end

function partId = promptPart()
  fprintf('== Select which part(s) to submit:\n', ...
          homework_id());
  partNames = validParts();
  srcFiles = sources();
  for i = 1:numel(partNames)
    fprintf('==   %d) %s [', i, partNames{i});
    fprintf(' %s ', srcFiles{i}{:});
    fprintf(']\n');
  end
  fprintf('==   %d) All of the above \n==\nEnter your choice [1-%d]: ', ...
          numel(partNames) + 1, numel(partNames) + 1);
  selPart = input('', 's');
  partId = str2num(selPart);
  if ~isValidPartId(partId)
    partId = -1;
  end
end

function [email,ch,signature,auxstring] = getChallenge(email, part)
  str = urlread(challenge_url(), 'post', {'email_address', email, 'assignment_part_sid', [homework_id() '-' num2str(part)], 'response_encoding', 'delim'});

  str = strtrim(str);
  r = struct;
  while(numel(str) > 0)
    [f, str] = strtok (str, '|');
    [v, str] = strtok (str, '|');
    r = setfield(r, f, v);
  end

  email = getfield(r, 'email_address');
  ch = getfield(r, 'challenge_key');
  signature = getfield(r, 'state');
  auxstring = getfield(r, 'challenge_aux_data');
end

function [result, str] = submitSolution(email, ch_resp, part, output, ...
                                        source, signature)

  params = {'assignment_part_sid', [homework_id() '-' num2str(part)], ...
            'email_address', email, ...
            'submission', base64encode(output, ''), ...
            'submission_aux', base64encode(source, ''), ...
            'challenge_response', ch_resp, ...
            'state', signature};

  str = urlread(submit_url(), 'post', params);
 
  % Parse str to read for success / failure
  result = 0;

end

% =========================== LOGIN HELPERS ===========================

function [login password] = loginPrompt()
  % Prompt for password
  [login password] = basicPrompt();
  
  if isempty(login) || isempty(password)
    login = []; password = [];
  end
end


function [login password] = basicPrompt()
  login = input('Login (Email address): ', 's');
  password = input('Password: ', 's');
end

function [login password] = quickLogin(login,password)
  cont_token = input(['You are currently logged in as ' login '.\nIs this you? (y/n - type n to reenter password)'],'s');
  if(isempty(cont_token) || cont_token(1)=='Y'||cont_token(1)=='y')
    return;
  else
    [login password] = loginPrompt();
  end
end

function [str] = challengeResponse(email, passwd, challenge)
  str = sha1([challenge passwd]);
end

% =============================== SHA-1 ================================

function hash = sha1(str)
  
  % Initialize variables
  h0 = uint32(1732584193);
  h1 = uint32(4023233417);
  h2 = uint32(2562383102);
  h3 = uint32(271733878);
  h4 = uint32(3285377520);
  
  % Convert to word array
  strlen = numel(str);

  % Break string into chars and append the bit 1 to the message
  mC = [double(str) 128];
  mC = [mC zeros(1, 4-mod(numel(mC), 4), 'uint8')];
  
  numB = strlen * 8;
  if exist('idivide')
    numC = idivide(uint32(numB + 65), 512, 'ceil');
  else
    numC = ceil(double(numB + 65)/512);
  end
  numW = numC * 16;
  mW = zeros(numW, 1, 'uint32');
  
  idx = 1;
  for i = 1:4:strlen + 1
    mW(idx) = bitor(bitor(bitor( ...
                  bitshift(uint32(mC(i)), 24), ...
                  bitshift(uint32(mC(i+1)), 16)), ...
                  bitshift(uint32(mC(i+2)), 8)), ...
                  uint32(mC(i+3)));
    idx = idx + 1;
  end
  
  % Append length of message
  mW(numW - 1) = uint32(bitshift(uint64(numB), -32));
  mW(numW) = uint32(bitshift(bitshift(uint64(numB), 32), -32));

  % Process the message in successive 512-bit chs
  for cId = 1 : double(numC)
    cSt = (cId - 1) * 16 + 1;
    cEnd = cId * 16;
    ch = mW(cSt : cEnd);
    
    % Extend the sixteen 32-bit words into eighty 32-bit words
    for j = 17 : 80
      ch(j) = ch(j - 3);
      ch(j) = bitxor(ch(j), ch(j - 8));
      ch(j) = bitxor(ch(j), ch(j - 14));
      ch(j) = bitxor(ch(j), ch(j - 16));
      ch(j) = bitrotate(ch(j), 1);
    end
  
    % Initialize hash value for this ch
    a = h0;
    b = h1;
    c = h2;
    d = h3;
    e = h4;
    
    % Main loop
    for i = 1 : 80
      if(i >= 1 && i <= 20)
        f = bitor(bitand(b, c), bitand(bitcmp(b), d));
        k = uint32(1518500249);
      elseif(i >= 21 && i <= 40)
        f = bitxor(bitxor(b, c), d);
        k = uint32(1859775393);
      elseif(i >= 41 && i <= 60)
        f = bitor(bitor(bitand(b, c), bitand(b, d)), bitand(c, d));
        k = uint32(2400959708);
      elseif(i >= 61 && i <= 80)
        f = bitxor(bitxor(b, c), d);
        k = uint32(3395469782);
      end
      
      t = bitrotate(a, 5);
      t = bitadd(t, f);
      t = bitadd(t, e);
      t = bitadd(t, k);
      t = bitadd(t, ch(i));
      e = d;
      d = c;
      c = bitrotate(b, 30);
      b = a;
      a = t;
      
    end
    h0 = bitadd(h0, a);
    h1 = bitadd(h1, b);
    h2 = bitadd(h2, c);
    h3 = bitadd(h3, d);
    h4 = bitadd(h4, e);

  end

  hash = reshape(dec2hex(double([h0 h1 h2 h3 h4]), 8)', [1 40]);
  
  hash = lower(hash);

end

function ret = bitadd(iA, iB)
  ret = double(iA) + double(iB);
  ret = bitset(ret, 33, 0);
  ret = uint32(ret);
end

function ret = bitrotate(iA, places)
  t = bitshift(iA, places - 32);
  ret = bitshift(iA, places);
  ret = bitor(ret, t);
end

% =========================== Base64 Encoder ============================
% Thanks to Peter John Acklam
%

function y = base64encode(x, eol)
%BASE64ENCODE Perform base64 encoding on a string.
%
%   BASE64ENCODE(STR, EOL) encode the given string STR.  EOL is the line ending
%   sequence to use; it is optional and defaults to '\n' (ASCII decimal 10).
%   The returned encoded string is broken into lines of no more than 76
%   characters each, and each line will end with EOL unless it is empty.  Let
%   EOL be empty if you do not want the encoded string broken into lines.
%
%   STR and EOL don't have to be strings (i.e., char arrays).  The only
%   requirement is that they are vectors containing values in the range 0-255.
%
%   This function may be used to encode strings into the Base64 encoding
%   specified in RFC 2045 - MIME (Multipurpose Internet Mail Extensions).  The
%   Base64 encoding is designed to represent arbitrary sequences of octets in a
%   form that need not be humanly readable.  A 65-character subset
%   ([A-Za-z0-9+/=]) of US-ASCII is used, enabling 6 bits to be represented per
%   printable character.
%
%   Examples
%   --------
%
%   If you want to encode a large file, you should encode it in chunks that are
%   a multiple of 57 bytes.  This ensures that the base64 lines line up and
%   that you do not end up with padding in the middle.  57 bytes of data fills
%   one complete base64 line (76 == 57*4/3):
%
%   If ifid and ofid are two file identifiers opened for reading and writing,
%   respectively, then you can base64 encode the data with
%
%      while ~feof(ifid)
%         fwrite(ofid, base64encode(fread(ifid, 60*57)));
%      end
%
%   or, if you have enough memory,
%
%      fwrite(ofid, base64encode(fread(ifid)));
%
%   See also BASE64DECODE.

%   Author:      Peter John Acklam
%   Time-stamp:  2004-02-03 21:36:56 +0100
%   E-mail:      pjacklam@online.no
%   URL:         http://home.online.no/~pjacklam

   if isnumeric(x)
      x = num2str(x);
   end

   % make sure we have the EOL value
   if nargin < 2
      eol = sprintf('\n');
   else
      if sum(size(eol) > 1) > 1
         error('EOL must be a vector.');
      end
      if any(eol(:) > 255)
         error('EOL can not contain values larger than 255.');
      end
   end

   if sum(size(x) > 1) > 1
      error('STR must be a vector.');
   end

   x   = uint8(x);
   eol = uint8(eol);

   ndbytes = length(x);                 % number of decoded bytes
   nchunks = ceil(ndbytes / 3);         % number of chunks/groups
   nebytes = 4 * nchunks;               % number of encoded bytes

   % add padding if necessary, to make the length of x a multiple of 3
   if rem(ndbytes, 3)
      x(end+1 : 3*nchunks) = 0;
   end

   x = reshape(x, [3, nchunks]);        % reshape the data
   y = repmat(uint8(0), 4, nchunks);    % for the encoded data

   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % Split up every 3 bytes into 4 pieces
   %
   %    aaaaaabb bbbbcccc ccdddddd
   %
   % to form
   %
   %    00aaaaaa 00bbbbbb 00cccccc 00dddddd
   %
   y(1,:) = bitshift(x(1,:), -2);                  % 6 highest bits of x(1,:)

   y(2,:) = bitshift(bitand(x(1,:), 3), 4);        % 2 lowest bits of x(1,:)
   y(2,:) = bitor(y(2,:), bitshift(x(2,:), -4));   % 4 highest bits of x(2,:)

   y(3,:) = bitshift(bitand(x(2,:), 15), 2);       % 4 lowest bits of x(2,:)
   y(3,:) = bitor(y(3,:), bitshift(x(3,:), -6));   % 2 highest bits of x(3,:)

   y(4,:) = bitand(x(3,:), 63);                    % 6 lowest bits of x(3,:)

   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % Now perform the following mapping
   %
   %   0  - 25  ->  A-Z
   %   26 - 51  ->  a-z
   %   52 - 61  ->  0-9
   %   62       ->  +
   %   63       ->  /
   %
   % We could use a mapping vector like
   %
   %   ['A':'Z', 'a':'z', '0':'9', '+/']
   %
   % but that would require an index vector of class double.
   %
   z = repmat(uint8(0), size(y));
   i =           y <= 25;  z(i) = 'A'      + double(y(i));
   i = 26 <= y & y <= 51;  z(i) = 'a' - 26 + double(y(i));
   i = 52 <= y & y <= 61;  z(i) = '0' - 52 + double(y(i));
   i =           y == 62;  z(i) = '+';
   i =           y == 63;  z(i) = '/';
   y = z;

   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % Add padding if necessary.
   %
   npbytes = 3 * nchunks - ndbytes;     % number of padding bytes
   if npbytes
      y(end-npbytes+1 : end) = '=';     % '=' is used for padding
   end

   if isempty(eol)

      % reshape to a row vector
      y = reshape(y, [1, nebytes]);

   else

      nlines = ceil(nebytes / 76);      % number of lines
      neolbytes = length(eol);          % number of bytes in eol string

      % pad data so it becomes a multiple of 76 elements
      y = [y(:) ; zeros(76 * nlines - numel(y), 1)];
      y(nebytes + 1 : 76 * nlines) = 0;
      y = reshape(y, 76, nlines);

      % insert eol strings
      eol = eol(:);
      y(end + 1 : end + neolbytes, :) = eol(:, ones(1, nlines));

      % remove padding, but keep the last eol string
      m = nebytes + neolbytes * (nlines - 1);
      n = (76+neolbytes)*nlines - neolbytes;
      y(m+1 : n) = '';

      % extract and reshape to row vector
      y = reshape(y, 1, m+neolbytes);

   end

   % output is a character array
   y = char(y);

end
